matrix

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[Mile] put together this stunning LED matrix watch, on which the stars of this show are the 256 monochrome 0603 LEDs arranged in a grid on its face. The matrix is only 1.4in in the diagonal and is driven by a combination of an LED driver and some shift registers. The brain is an ATmega328p. We appreciate the extra effort taken to add a USB to UART adapter so the mega can be programmed over USB. It also contains all the necessary circuitry to charge and maintain the lithium battery inside safely.

Input into the device is done with a hall effect sensor which keeps the build from having any moving parts. The body is a combination of 3D printed parts and really fetching brass details connecting to the band.

If it weren’t over the top enough the build even has an ambient light sensor so the display can dim or brighten depending. We bet [Mile] is pretty proud to wear this on their wrist.

LED cubes are all the rage right now, and rightly so given the amount of work that goes into them and the interesting things people find to do with them. Not content to make yet another position-sensitive display or an abstract design, though, [Greig Stewart] opted for something a bit more ambitious: an LED cube with a playable game of Castlevania.

As ambitious projects often do, this one required leveraging the previous art, some of which we’ve featured before. [Greig] pulled inspiration and information from cube builders like [polyfloyd], [Greg Davill], and [kbob] to put the six 64-LED matrix panels to work. Getting the structural elements figured out was an early stumbling block, but [Greig] pulled it off with 3D-printed brackets and a hinge that’s a work of art in itself; the whole thing looks like something the Borg would have built. The Raspberry Pi inside made a Gameboy emulator possible, and his first stab at it was to have six different games running at once, one on each panel. He settled on just one game, the classic side-scroller Castlevania, played on just four of the panels. Some wizardry was required to de-scroll the game so that the character walks around the cube rather than having the background scroll; you can check out the results in the clip below.

Currently, the cube sits on a lazy susan with a small motor controlling the swiveling in response to a foot control. [Greig] wants to put the motor under control of the game so that physical scrolling is synced with gameplay; we heartily endorse that plan and look forward to the results.

He had a project in MicroPython that needed a very fast FFT on a micro controller, and was looking at all of the options when it occurred to him that a more structured approach like the one we all know and love in CPython would be possible on a micro controller too. He thus ended up with a python library that could do the FFT 50 times faster than the the pure Python implementation while providing all the readability and ease of use benefits that NumPy and Python together provide.

Of all the things you never would have guessed you’d need just ten years ago, a YouTube subscriber counter would probably rank highly. You would have guessed that the little hits of dopamine accompanying each tick upward of a number would be so addictive?

As it turns out, lots of people wanted to keep a running total of their online fans, and a bewilderingly varied ecosystem of subscriber counters has cropped up. All of them rely on the API that YouTube exposes for such purposes, which as [Brian Lough] points out is about to change and break every subscription counter ever made. In the YouTube sub counter space, [Brian] is both an enabler – he built an Arduino wrapper to fetch YT sub counts easily – and a serial builder of displays for other YouTubers. The video below shows a collection of his work, many based on RGB LED matrix display, like the one used in his Tetris-themed sub counter. They’re all well-built, nice to look at, and sadly, destined for obsolescence sometime in August when the API changes.

The details of the API changes were made public in April, and for the subs count it amounts to rounding the count and displaying large counts as, for instance, 510k as opposed to 510,023. We’re confident that [Brian] and other display builders will be able to salvage some of their counters with code changes, but others will probably require hardware changes. Thanks, YouTube.

When deadlines loom and your future is on the line, do what top college students through the ages have always done: procrastinate! [Simen] and [Amund] did that in grand style by starting a YouTube channel, delightfully and aptly named “Applied Procrastination”, wherein they plan to avoid their responsibilities as long as possible in favor of making a large-scale ferrofluidic display panel. (Video, embedded below.)

We suppose we should encourage them to hit the books, but honestly they look like they’re having much more fun and learning more than they would in class. The idea isn’t new; we’ve seen ferrofluid clocks before, after all. [Amund] and [Simen] have grander plans for their display, but they’re wisely starting small with basic experiments. They had an early great idea to use a double-pane window as a tank for their display, but coatings on the inside of the glass and the aluminum frame conspired to cloud the display. They also did some tests to make sure they can control 252 electromagnets safely. They did manage to get a small test display working, but really the bulk of the video is just them playing with magnets and ferrofluid. And again, we’re OK with that.

It looks like this is going to be an interesting project, with hopefully regular updates to the channel now that summer break is upon us. Unless they find something else to do, of course.

Constrained builds are often the most fun. Throw an artificial limit into the mix, like time limiting your effort or restricting yourself to what’s on hand, and there’s no telling what will happen.

[bitluni] actually chose both of those constraints for this ping pong ball LED video display, and the results are pretty cool, even if the journey was a little rough. It seems like using sheet steel for the support of his 15 x 20 Neopixel display was a mistake, at least in hindsight. A CNC router would probably have made the job of drilling 300 holes quite a bit easier, but when all you have is a hand drill and a time limit, you soldier on. Six strings of Neopixels fill the holes, a largish power supply provides the 18 or so amps needed, and an Arduino knock-off controls the display. The ping pong ball diffusers are a nice touch, even if punching holes in them cost [bitluni] a soldering iron tip or two. The display is shown in action in the video below, mostly with scrolling text. If we may make a modest suggestion, a game of Pong on a ping pong ball display might be fun.

Like many other classics it’s easy to come up with ways to ruin Tetris, but hard to think of anything that will make it better. Adding more clickiness is definitely one way to improve the game, and playing Tetris on a flip-dot display certainly manages to achieve that.

The surplus flip-dot display [sinowin] used for this version of Tetris is a bit of an odd bird that needed some reverse engineering to be put to work. The display is a 7 x 30 matrix with small dots, plus a tiny green LED for each dot. Those LEDs turned out to be quite useful for replicating the flashing effect used in the original game when a row of blocks was completed, and the sound of the dots being flipped provides audio feedback. The game runs on a Teensy through a custom driver board and uses a Playstation joystick for control. The video below, in perfectly acceptable vertical format, shows the game in action and really makes us want to build our own, perhaps with a larger and even clickier flip-dot display.